Low-cost, high-gain antenna reflector designs exist in the prior art. One such design is disclosed in U.S. Pat. No. 3,832,717 issued to the inventor hereof Aug. 27, 1974. That design offered the advantages of low cost, light weight and convenient assembly in the field while providing relatively high gain performance up to approximately 4 GHz. However, that reflector, comprising a plurality of generally triangular petals assembled in slightly overlapping relationship, attained only a "quasi-paraboloid" shape which reduces its gain characteristics above 4 GHz. In order to achieve useable gain at frequencies in the 12 GHz region, a reflector having a conformation more closely approaching a true paraboloid is necessary.
True parabolic antennae typically require substantial truss support structure and are expensive to manufacture. The parabolic reflector of the present invention requires no support truss and, by improving the basic design concept of the above-mentioned U.S. patent, achieves substantially parabolic shape over the entire surface of the reflector without appreciably increasing manufacturing cost, complicating field assembly or increasing shipping weight.
One embodiment of the present invention comprises a plurality of greatly overlapping, generally triangular-shaped petals having precisely sized and positioned holes in the overlap region through which a set of fasteners are inserted to locate one petal relative to the next and to bend adjacent petals elastically to provide curvilinear transverse shape therein. For this embodiment the petals may be interlaced or alternately overlayed. Another embodiment of the present invention comprises a layer of generally triangular shaped petals coupled to a second fully overlapping layer of similar shaped petals, the layers being rigidly held together in substantially parabolic conformation by fasteners inserted through commonly and precisely sized and positioned holes through the petals of both layers. For each embodiment, a rigid, segmented exterior rim formed to receive the outer edges of the assembled petals provides the necessary mechanical structure for mounting and positioning the reflector and for maintaining mechanical integrity over a wide range of environmental conditions.
Before assembly of either configuration reflector, each petal is essentially a flat sheet of light-weight, flexible, relatively thin, electromagnetically reflective material such as aluminum. The ultimate reflector configuration is determined by the precisely positioned fasteners in each petal or, alternatively in the case of the two-layer configuration wherein the inner layer petals edgewise abutt, by the shape of the abutting petal edges. Thus, by controlling the locating of the holes in the petals and the shape of the petal edges, the shape of the reflector is controlled and adjusted as desired.